Alkylation process



Patented Feb. 22, 1949 ALKYLATION PROCESS Francis T. Wadsworth, TexasCity, and Robert J. Lee, La Marque, Tex., assignors to Pan AmericanRefining Corporation, New York, N. Y., a

corporation of Delaware Application August 9, 1945, Serial No. 609,882

6 Claims.

This invention relates to a process for the conversion of hydrocarbons.More particularly it relates to a process for the alkylation ofpolycyclic hydrocarbons. In one specific embodiment this inventionrelates to the alkylation of polymethyl naphthalenes with olens.

One object of our invention is to provide a. process for the alkylationof alkyl polycyclic hydrocarbons with olens wherein side reactions areminimized. Another object of our invention is to provide a process forthe alkylation of alkyl polycyclic aromatic hydrocarbons with olensunder conditions conducive to the production of high yields ofalkylation products, Which conditions avoid destruction of thealkylation catalyst. An additional object of our invention is to providea process for the alkylation of aromatic hydrocarbons, especiallynaphthalene and its derivatives, under conditions and with a catalystadapted to avoid or minimize the production of condensed ring compounds,such as binaphthyls and the like. Still another object of this inventionis to provide a process for the employment of substantially anhydroustoluene sulfonic acids under carefully controlled conditions for thealkylation of polycyclic hydrocarbons with olens. An additional objectof our invention is to provide novel alkylated polycyclic aromatichydrocarbons. Further objects will become apparent as the description ofour invention proceeds.

Briey, We have discovered that polycyclic hydrocarbons, such asnaphthalene, methyl naphthalenes and polymethyl naphthalenes can bealkylated with oleins in the presence of substantially anhydrous toluenesulfonic acids to produce high yields of alkylated polycyclichydrocarbons having molecular weights equal to the molecular weights ofthe olens and polycyclic hydrocarbons which have participated in thealkylation reaction. Particularly, We have discovered operatingconditions for this alkylation process which are conducive to theobtainment of high yields of desired alkylates at high alkylationreaction rates. The operating conditions which we use obviateundesirable side reactions of the type hitherto encountered inalkylation processes of this nature, viz., olen polymerization andexcessive catalyst destruction. We can use a Wide variety of alkylpolycyclic hydrocarbons in our process. Suitable sources of alkylpolycyclic aromatic hydrocarbons for use in our process are synthetichydrocarbon fractions obtained by the catalytic conversion of petroleumoils with catalysts comprising at least one metal oxide selected fromgroups 2 to 6, inclusive, of the periodic table, particularly silica,although polycyclic hydrocarbons from other sources, e. g., coal tar,can also be used.

Specifically, a suitable process for the production of alkyl polycyclicaromatic hydrocarbons is the hydroforming process. In this process apetroleum naphtha, which may be a virgin or cracked naphtha or mixtureof both, is converted to aromatic hydrocarbons by contact with a solid,porous dehydrogenation catalyst at a temperature in the range of about850 F. to about 1050 F., preferably in the presence of hydrogen.Suitable catalysts are oxides of metals of groups 2 to 6 of the periodicsystem, particularly oxides of 6th group metals such as chromium andmolybdenum, preferably supported by alumina or magnesia. Excellentcatalysts can be prepared by depositing about 4 to about 10% ofmolybdenum oxide upon an activated alumina. Suitable space velocitiesfor hydroforming fall Within the range of about 0.2 to about 4 volumesof the liquid charge stock per hour per volume of catalyst space. About0.5 to about 8 mols of hydrogen can be charged to the process With eachmol of naphtha feed stock. In addition to a high octane number naphtha,the hydroforming process produces a fraction which boils above thenaphtha range, for example, in the range of about 425 to about 650 F.,which is known as hydroformer bottoms. We can use the entire hydroformerbottoms or selected fractions thereof as feed stock for our process.

Hydroformer bottoms comprises a complex mixture of alkyland polyalkylpolycyclic aromatic hydrocarbons, including relatively large proportionsof monoand polymethyl naphthalenes. Although the constitution ofhydroformer bottoms fractions may vary to a minor extent, depending uponthe specific catalyst, the age of the catalyst, the specificconstitution of the feed stock, etc., remarkably uniform hydroformerbottoms can be produced in a commercial hydroformer plant.

A representative hydroformer bottoms fraction exhibits the followingphysical properties:

A.P.I. gravity l1. 0 Refractive indexND2D l. 5911 Specific dispersion.o264 Specific gravity 2%0 989 It Will be noted that the hydroforrnerbottoms have a rather narrow boiling range except for the last 20%.Distillation of the bottoms with fire and steam accompanied by somefractionation was carried out, 8 volume percent distillate fractions ofthe bottoms being separated. The refractive indices and specificdispersions of the distillate fractions of the hydroformer bottoms areshown in the following table:

Percent of Refractive Specific 4 Tractlon Prgffrlller Index, N D20.Dispersion The precise chemical characterization of hydroformer bottomsor specific fractions thereof constitutes a difficult analyticalproblem. The general nature of the hydrocarbons present in hydroformerbottoms Was revealed by extraction of the bottoms with nitromethane,which is a solvent having high solvent capacity for polycyclic and alkylpolycyclic aromatic hydrocarbons under conditions of temperature andsolvent/oil ratios under which it dissolved Vsubstantially nonon-aromatic or monocyclic aromatic hydrocarbons. The hydroformerbottoms were fractionally extracted and the boiling points, refractiveindices and specific dispersions of the extracts were determined. Fromthe data so obtained, together with distillation analyses and chemicalcharacterization, it appears that the hydroformer bottoms have thefollowing composition (by volume) z Anthracene and alkylated anthracenes1Dimechyl and higher alkyl groups.

It is to be remembered that the above values are only approximate andare given as our best estimate of its composition.

A variety of olens which may be either normally gaseous or liquid, canbe employed in our alkylation process. Normally gaseous olefinsconstitute a preferred feed stock in our process when it is desired toproduce alkylates having value as plasticizers for high molecular Weightresins and plastics, for example, natural rubber, butadiene rubbers suchas butadiene-styrene copolymerizates (GR-S) or butadiene-acrylonitrilecopolymerizates (GR-N), polystyrene, polyvinyl halide resins, celluloseand cellulose derivatives, etc. We can use clef-ins such as propylene,butylenes, amylenes, hexenes, and the like. We can 4 also use mixturescontaining two or more olens and/or other hydrocarbons, such as arefound in Ipetroleum refinery hydrocarbon fractions.

The catalyst employed in our alkylation process is a substantiallyanhydrous toluene sulfonic acid. The catalyst may be ortho,V meta, orpara-toluene sulfonic acid, but We prefer to use a technical toluenesulfonic acid which contains more than one isomer and may contain allthree. We have found that the substantially anhydrous toluene sulfonicacids are much more soluble in hydrocarbons than hydrous toluenesulfonic acids and `can be used as homogeneous catalysts underconditions Where hydrous toluene sulfonic acids are'quite immisciblewith hydrocarbonA feed stocks. Furthermore, anhydrous toluene sulfonicacids appear to induce higher reaction rates than the hydrated acids. Infact, in many instances, hydrated toluene sulfonic acid has been foundto be substantially devoid of catalytic alkylation activity. Typicaltoluene sulfonic acids which We have employed as catalysts for thealkylation of alkyl polycy-clic aromatic hydrocarbon with olens vhavethe following properties:

Neutralization equiv. (theory: 172) Density, grams/inl. at 84.9 F

Refractive index: y

(a) Of 11.4% aqueous solution 1.352

brown color `We have found that although we may use as little as 1 molpercent, it is desirable to use at least 3 mol percent, preferably 10mol percent of toluene sulfonic acid based on the alkyl polycyclichydrocarbon employed as feed stock. Increased yconcentration of toluenesulfonic acid in the reaction zone increases the rate of the alkylationreaction. Thus, Vthe Yemployment of 10 mol percent of toluene sulfonicacid induced a higher rate of alkylation than 3 mol percent. We can use20 mols of toluene sulfonic acid per 100 mols of alkyl polycyclichydrocarbon, or-even more.

The rate of alkylation is also affected by the specic olefin feed stock.We have found that the rate of alkylation is reduced with increasingmolecular weight of the olen feed stock. Thus, propylene alkylates analkyl polycyclic aromatic hydrocarbon at a considerably faster rate than`butene-l, and butene-l alkylatesy more rapidly than pentene-l. Dataillustrating the effects of catalyst concentrationY and specific oleiinson the rates of alkylation are set forth vin Table I. In the experimentswhich yielded the data -set forth in Table I, a Well-stirred solution oftechnical toluene sulfonic acid in a fraction of hydroformer bottomsboiling in the range of about 480 to 530 F. was in each case maintainedat 265 F., While the pure olefin was introduced in slight excess of thereaction rate. The fraction ofAhydroformer bottoms that Was usedcomprised' a substantial proportion of dimethyl naphthalenes. Themaximum rate rof olefin introduction was 0.006 cubic foot per minute fora 15 mol aromatic hydrocarbon charge containing 10 mol Ypercent oftechnical ytoluene sulfonic acid. The data presented inTable I show that10'mo1 percent toluene -sulfonia acid induced an enhanced rate ofalkylation as compared with 3 mol percent of toluene Sinfonie acid.

TABLE I Efect of catalyst concentration and nature of l olefin on theallez/lation of dimethyl naphtha- Zenes Temperature: 265 F.Charge stock:480-530 F. fraction of hydroformer bottoms Mols of Olefln Absorbed/Molof Hydrocarbon] Hour Time Hours 3% catalyst 10% catalyst PropyleneButene-l Butene-l olefin/mol of Aromatic 1. 81 1. 82 2. 04 58 Total time25 47. 5 14 12 The optimum temperatures for the use of substantiallyanhydrous toluene sulfonic acid catalysts for alkylating alkylpolycyclic hydrocarbons with olens lie within the range of about 265Penetene-l to about 300 F. We have found that in admixture with alkylpolycyclic hydrocarbons and olens, toluene sulfonic acids begin -t-odecompose at a substantial rate at temperatures above about 300 F.,although in the absence of polycyclic hydrocarbons and `oleiinsconsiderably higher decomposition temperatures are indicated. It isprobable that decreased alkylation rates observed at temperatures inexcess of 300 F. are attributable to the decomposition of toluenesulfonic acids. However, we do not intend to be bound by any theoryregarding the alkylation reactions.

Representative data indicating the effect of temperature on the rate ofalkylation of alkyl polycyclic hydrocarbons with olens are illustratedin the graph on the accompany drawing. The data were obtained by againalkylating a fraction of hydroformer bottoms boiling in the range ofabout 480 to about 530 F., comprising a substantial proportion ofdimethyl naphthalenes, using a concentration of 10 mol percent oftechnical toluene sulfonic acid per mol of dimethyl naphthalene in thefeed stock. Butene-l was introduced into the alkylation zone at a rateslightly in excess of its absorption (reaction) rate. From the graph onthe accompanying drawing it will be evident that alkylation proceeded ata slow rate at 212 F. and at a rapid rate at 302 F. However, at 392 F.,the alkylation rate was appreciably lower than the rate at 302 F. Theoptimum alkylation rate' is achieved and the recovery of toluenesulfonic acid catalyst for recycle to the alkylation zone is maximum attemperatures in the range of about 265 to about 300 F.

The data in Table II are advanced as practical illustrations of theresults obtainable by our improved alkylation process, but are notintended unduly to li-mit our invention.

TABLE II Preparation and properties of propylated and butt/lated alkylnaphthalenes Era'mple l 2 3 4 5 Product. mono and dibutyldibutyl crrglt11110110 and mono and dibutyldipropyl.

Reactor 5 liter glass 5 liter glass 2 gallon steel 50 gallon steel 3liter glass. Alkylation Conditions:

Mol percent toluene sulfonic acid 8.

catalyst. Pressure Atm 70 mm. Hg. Temperature, F 26o-265.

Time, hours 80 Mols olen absorbed/mol hydroormer bottoms. Charge Stock:

Olefm Hydroiormer bottoms fraction, boiling range (F.) at 1 atm.

92 (in excess). 2.14.

Butene-l Mixed B-B 1 Mixed B-B 1 Refinery propylenes (47.9% propylene).7-554.

Total 143 Dialkylated Product, Wt. Percent oi Theoretical Yield. Product1- 3 2 4 5. o 248-338/1 mm. 608-622/760 mm 6l2-653/772 mm. BollingRanger F mm }336383/2 111m- 541'633/760 mmh- {gggogs/l mm" ggggS/l mm .50.9489 0.944 0.9390. Light Yello Light Yellow (1% Light Yellow (1V92ASTNI). 9 ASTM). Weight percent Aromatics by sul- 98.6 96.6 8 5fonction i. Iodine No. (Wijs) 0. Viscosity at 100 F., Centistokes 46.5.Saybolt Viscosity, Universal (sec,- 215.

ands/100F.)

l Renery butane-butylene stream containing 41% olefms. 2 Method tends togive low values in the high ranges of aromatic t 3 Average molecularWight 256. The theoretical molecular weight of a dibutyl dimethylnaphthalene is 268.

In 'Table II, the hydroformer bottoms fraction boiling in the range of437 'to .554 F. comprised predominantly a mixture of mono-, di, andtrlmethyl naphthalenes. The hydroformer .bottoms fraction boiling at 482to 527 F. comprised predominantly dimethyl naphthalenes. Details ofoperating procedures used in obtaining the data set forth in Table IIwill be Set forth below.

Example 1 A sample of butylated hydrofor-mer bottoms was prepared byalkylation at 265 F. of la 3 mol percent solution of technical toluenesulfonic acid in dimethylnaphthalenes (482-527 F. fraction fromhydroformer bottoms). The solution was placed in a liter, 3 neck askfitted with an eicient mechanical stirrer, a water Condenser and a gasdistributor which introduced the gas through small holes beneath thesurface of the liquid. The gas was metered in at a rate slightly fasterthan that at which it was absorbed. Alkylation was continued until 1.2mols of olen per mol of hydroformer bottoms, calculated asdimethylnaphthalene, had been absorbed. Beyond this point the absorptionof butylenes was slow. Alkylati'on was `then stopped and when flaskcontents had cooled the catalyst was washed out with dilute alkali andthen with water. When vacuum distillation of the dried mixture wasattempted, the presence of a white crystalline solid was noted in thedistillate; some had also solidied in the condenser. It is believedvthat this solid is formed by the decomposition of esters of toluenesulfonic acid at the high pot temperatures. The distillation wascontinued, however, at total take-off, allowing the remaining esters todecompose until the temperature reached 410 F. at 3 to 4 mm. mer-curypressure. v The toluene sulfonic acid was washed out of the distillatewith dilute alkali and nonalkylated .and unreacted hydrocarbons wereremoved by topping-this distillate through a 60 x 2.5 cm. column packednwith A1/3 inch Fenske helices to an overhead temerature of 450 F'. at200 mm. mercury pressure. The product was diluted with isopentane anddecolorized by filtering through clay. After solvent removal the mixedmcnoand dibutyl dimethylnaphthalene yield based on crude butylat- 50 edproduct was 75 weight percent. Physical properties were determined andare listed in Table II under product 1.

Example 2 Product 2 of Table II was prepared bythe alkylation of a widercut of hydroformer bottoms (mono, di, and tri-methylnaphthalenes,boiling range 437-554 F.) with Dure butene-l, us-

ing v mol percent of anhydrous 'toluene sulfonic acid catalyst. In thispreparation, butylation was continued until the product contained anaver` Example J3.

For this alkylation a refinery stream `of `butanes-butylenes was used inplace of pure butene-l, and found Ato be satisfactory. `The refinerystream, containing 41% of oleiins, was dispersed well beneath thesurface of the liquid aromatic hydrocarbons by means of a distributortube. The exhaustgas, from which most ofthe olens had been removed, wasallowed to escape from a pressure reducing Valve located at the top ofthe reactor. After the injection of the olenic gas stream wasdiscontinued, the contents of the alkylation reactor were maintainedwith stirring at the reaction temperature between 3 and 4 hours. Thereactor contents were thereafter withdrawn, cooled, and free toluenesulfonic acid was removed by Washing with an aqueous vsolution ofcaustic soda. The specific constants listed in Table II for product 3are for the crude unfractionated material which contains a small amountof unreacted feed stock; hence they are at slight variance 4with otherproduct samples.

Example 4 The liquid charging stock was 17.5 gals. (66.7 kg.) of a mixedmono, di-, and trimethyl naphthalene fraction of hydroformer bottoms. Tothis charging stock there was added 10 mol percent (7.35 kg.) oftechnical toluene sulfonic acid. The butano-butenes gas stream was firstintroduced at the rate of 0.2 cubic feet per minute. Shortly 3-thereafter the rate was increased to 0.5 cubic feet per minute. A smallproportion of polymer having an average molecular weight of .126 wasproduced. The mol ratio of olefin converted vto polymer to olenconverted to alkylate was 0.0645. 40 The products were worked up in themanner described in Example 3 and were then fractionated.

Eample 5 Table II indicates that dipropylation of ahydroformer bottomsfraction can be effected under conditions similar to those employed withbutylenes to yield a similar product. Upon completion of the desiredalkylation reaction, propylene injection was discontinued and the`reaction mixture was stirred at the alkylation temperature for anadditional 4 hours to decompose yesters of toluene sulfonic acid whichare present in the alkylation reaction mixture. Thereafter thereactionmixture was allowed to cool :to room temperature and finished asdescribed in Example 3. From the data of Table II, it will be seen thatmonoor dialkylation of hydroformer bottoms fractions can Ibeaccomplished quite read-ily under '60 mild reaction conditions in thepresence of substantially anhydrous toluene sulfonic acids. The specificcatalyst used was a mixture of technical `toluene sulfonic acids, whoseproperties 'have lbeen described above. It will also be observed thatpetroleum refinery mixtures of butenes-butanes vcan be used Aasalkylating agents with substanv.tially as good results as those obtainedwhen pure butene-l is used.

From a comparison of Vthe data in Table II it will be observed that thebutylated product is characterized by high viscosity (-300 secondsSaybolt Universal at 100 F.) and low volatility or high boiling range at1-2 mm. .mercury pres- Our alkylation process can be operated batchwise, multistage, or continuously. The toluene sulfonic acid catalystcan be separated from the alkylation products intermittently orcontinuously, and recycled to the alkylation reactor. A particularlysuitable method for recovering the toluene sulfonic acid catalyst fromthe reaction mixture, especially where relatively large quantities ofcatalyst are used, e. g., 10 to 20 mol percent, comprises diluting witha saturated aliphatic material in the liquid state, e. g., a hydrocarbonsuch as liquid propane, butanes, pentanes, hexanes, heptanes,cyclohexane, etc., or mixtures containing two or more of thesehydrocarbons, paranic naphthas, kerosene, gas oil or the like. Upon theaddition of a suiiicient volume of saturated aliphatic material, usuallybetween about 0.25 and about 3 volumes per volume of the alkylationreaction mixture, the toluene sulfonic acid catalyst separates as alower layer in substantially anhydrous condition and can be recycled asan alkylation catalyst without modification. Layer separation can beeiected conveniently at temperatures within the range of about 50 toabout 150 F. e. g., at room temperature. The small proportion, e. g., 1to 3% of toluene sulfonic acid which remains in solution in the alkylatecan be removed by washing with water or alkalies prior to fractionatingthe alkylate. Unconverted feed stocks can be recovered and recycled inproper proportions to the alkylation reactor. Over-alkylation can beavoided by recycling products of undesirably high molecular weight tothe alkylation reactor.

Although our invention has been described with specific reference to thealkylation of hydroormer bottoms, it is not thus limited and can beapplied to the alkylation of alkyl polycyclic Ihydrocarbons fromdiierent sources. Thus, it may be applied to alkyl polycycylichydrocarbons derived from certain crude petroleum oils by extractionwith selective solvents. Alkyl polycyclic hydrocarbons derived from coaltars, e. g., alkyl naphthalene fractions, are desirable feed stocks forour improved alkylation process. Alkyl polycyclic aromatic hydrocarbonsare also present to a considerable extent in cracked cycle stocksproduced by cracking high boiling petroleum oils such as gas oils,preferably with catalysts. Cracking with solid cracking catalystscomprising one or more oxides of metals selected from groups 2 6,inclusive, e. g., silica, of the periodic table may be eiected attemperatures of the order of about 850 to 1050 F. and pressures ofatmospheric to 50 p. s. i. or even higher. A suitable cracking catalystis active silica promoted with about 5 to about 30% of active alumina ormagnesia. Also, activated clays may be used as catalysts. A lkylpolycyclic aromatic hydrocarbons may be concentrated from cracked cyclestocks by a variety of selective solvents. Suitable selective solventsinclude nitromethane, nitroethane, ethylene glycol monoethyl ether,diethylene glycol monoethyl ether, diethylene triamine, dipropyleneglycol, methanol, ethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, morpholine ethanol, triethylene tetramine,tetraethylene pentamine, etc.

The physical properties of aromatic hydrocarbons extracted by aselective solvent from a cycle 'stock produced by catalytically cracking35 A. P. I. Mid-Continent gas oil are:

A.P.I. gravity 9.6 Refractive index ND20 1.5960 Specific dispersion 267Speclc gravity l-o-C 1.007 A.S.T.M. distillation (F.):

Initial 420 5 10% 464 20 478 30 494 40 512 50 526 6o 544 10 70 570 80%600 90 658 Max 732 The alkylation products, particularly the mono- 15and dibutylated methyl naphthalenes, produced by the process of ourinvention are novel and useful. Because of their low volatility and highviscosity, they are especially adapted for use as plasticizers in highmolecular Weight resins and plastics such as natural rubbers,butadienestyrene rubbers, butadiene-acrylonitrile rubbers, celluloseplastics, etc. Alkylated methyl naphthalenes, e. g., dipropyl, dibutyl,and diamyl dimethyl naphthalenes, can be used in combination with otherplasticizers, e. g., ester type plasticizers such as dibutyl phthalate,in plasticizing rubbers, e. g., butadiene-acrylonitrile rubbers.Alkylated methyl naphthalenes, as produced by the process of ourinvention, can also be employed in compositions for impregnating woodand other brous materials to prevent or inhibit attack by termites or bymarine organisms. Suitable imprcgnating compositions can containcreosote or coal tar in addition to the alkylated methyl naphthalenes.Alkylation products of our invention can also be used as insecticides,e. g., for chinch bugs and termites, alone or in combination with otherinsecticidal materials. The alkylated methyl naphthalenes can also besulfonated to yield sulfonates whose salts, e. g., the sodium andpotassium salts are wetting, re-wetting, detergent or emulsifyingagents. The alkylated methyl naphthalenes can also be employed aslubricants alone or in combination with other lubricants. Alkylatedmethyl naphthalenes can be employed in quenching oils. As to theforegoing description of uses for the alkylation products which can beproduced by our process, it will be understood that chemical derivativesof the alkylation products can also be employed, e. g., halogenatedderivatives, alkoxy derivatives, chloromethyl derivatives, etc.

It will be evident that we have set forth a highly advantageous processfor the alkylation of alkyl polycyclic hydrocarbons characterized byhigh yields of desirable alkylates, low catalyst consumption and theavoidance of undesirable side reactions.

We claim:

1. A process for the alkylation of polycyclic aromatic hydrocarbonswhich comprises introducing an olefin into an alkylation Zone andcontacting said olen in said alkylation zone with polycyclic aromatichydrocarbons and at least 3 mol percent of a substantially anhydroustoluene sulfonic acid at a temperature in the range of about 265 toabout 300 F. under suiiicient pressure to maintain a liquid phase insaid alkylation zone, diluting alkylation reaction products with asaturated hydrocarbon, and separating a phase comprising substantiallyanhydrous toluene sulfonic acid.

2. A process for the alkylation of a polycyclic aromatic hydrocarbonwhich comprises contacting an olen in an alkylation Zone with apolycyclic aromatic hydrocarbon and a substantially anhydrous toluenesulfonic acid catalyst at an alkylation temperature underv suflicientpressure to maintain. a liquid phasev in said ralkyl'aton zone, dilutingthe alkylation reaction mixture with a saturated hydrocarbon andseparating a distinct phase comprising substantially anhydrous toluenesulfonic acid.

3. The process of claim 2 wherein the olen is a normally gaseous olefincontaining at least three carbon atoms in the molecule.

4. The lprocess of claim 2 whichv comprises the additional step ofrecycling substantially anhydrous toluene sulfonic acid recovered fromthe alkylation reaction mixture to said alkylation zone.

5'. 'The process of claim 1 wherein the polycyclic aromatic hydrocarbonsare contained in a fractioncomprising a substantial proportion ofmethylnaphthalenes, said fraction boiling between about 437 F. and about554 F. at 1 atmosphere.

6. The process of claim 2 wherein the polycyclic I2 Y aromatichydrocarbons: aref contained in a. fraction comprising a substantialproportion of inethylnaphthalenes,f said fraction boiling between about437 F. andk about 554 F. at 1 atmosphere.

FRANCIS T. WADSWO-RTH. ROBERT J'. LEE.

REFERENCES CITED The following references are ofr record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,741,472 Michel 1 Dec. 31, 19292,014,766 Isham Sept. 17, 1935 2,385,303 Schmerling Sept. 18, 19452,386,892 Schaad Oct. 16, 1945 2,390,835V Hennion et al. Dec. 11, 19452,390,836 Hennion et al Dec. 11, 1945 2,395,976 Shankland Mar- 5, 19462,411,578 Lieber Nov. 26, 1946 Certificate of Correction Patent No.2,462,792. February 22, 1949.

FRANCIS T. WADSWORTH ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Columns 5 and 6, Table Il, column numbered 4, opposite Boiling Range,OF. for 608-622/760 mm read 608-662/760 mm;

and that the said Letters Patent should be read With this correctiontherein that the same may conform to the record of the ease in thePatent Ofice.

Signed and sealed this 28th day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant ommssz'oner of Patents.

